Microelectromechanical structures (MEMS) and other microengineered devices are presently being developed for a wide variety of applications in view of the size, cost and reliability advantages provided by these devices. Many different varieties of MEMS devices have been created, including microgears, micromotors, and other micromachined devices that are capable of motion or applying force. These MEMS devices can be employed in a variety of applications including hydraulic applications in which MEMS pumps or valves are utilized and optical applications which include MEMS light valves and shutters.
MEMS devices have relied upon various techniques to provide the force necessary to cause the desired motion within these microstructures. For example, cantilevers have been employed to apply mechanical force in order to rotate micromachined springs and gears. In addition, some micromotors are driven by electromagnetic fields, while other micromachined structures are activated by piezoelectric or electrostatic forces. Recently, MEMS devices that are actuated by the controlled thermal expansion of an actuator or other MEMS component have been developed. For example, U.S. patent application Ser. Nos. 08/767,192; 08/936,598, and 08/965,277 are assigned to MCNC, the assignee of the present invention, and describe various types of thermally actuated MEMS devices. In addition, MEMS devices have been recently developed that include rotational connections to allow rotation with less torsional stress and lower applied force than found with torsion bar connections. For instance, U.S. patent application Ser. No. 08/719,711, also assigned to MCNC, describes various rotational MEMS connections. The contents of each of these applications are hereby incorporated by reference herein.
Regardless of the actuation source, most MEMS devices provide generally linear motion. As such, a need exists to provide MEMS devices that are capable of nonlinear motion, including rotational motion. MEMS devices can thereby be employed in a broader range of applications.